© Getty Images
In what turned out to be an epic encounter at the Parramatta Stadium, it seemed that visiting Roar were destined for a spot in next weekend's showpiece match when they raced into a 3-0 lead within the opening 23 minutes.
Then, after leading goalscorer Jamie Maclaren added a third goal, the outcome looked inevitable.
Dutch midfielder Castelen then took centre stage after the restart as he completed his hat-trick to put his side 4-3 in front with goals in the 53rd and 59th minutes, the latter of which was a half-volley from the edge of the box.
However, in keeping with the drama, there were nine minutes remaining when Brisbane's Maclaren stole in at the back post to force extra time.
Both sides had chances during the added 30 minutes to nab the all-important ninth goal of the game, which eventually went the way of the Wanderers in the 102nd minute.
His team will now battle it out with Adelaide United to lift the trophy.